1. Field of the Invention
The present invention relates generally to gyroscopic instruments and is more particularly concerned with two-degree-of freedom flexure suspended free-rotor gyroscopes.
2. Description of the Prior Art
Flexure suspended free-rotor gyroscopic devices are found in U.S. patents assigned to Sperry Rand Corporation including:
W. G. Wing--U.S. Pat. No. 2,719,291--"Rate of Turn Gyroscope", issued Sept. 27, 1955, PA2 T. R. Quermann--U.S. Pat. No. 3,529,477--"Gyroscopic Rotor Suspension", issued Sept. 22, 1970, PA2 T. R. Quermann--U.S. Pat. No. 3,557,629--"Pick-Off and Torquing Device", issued Jan. 26, 1971, and PA2 T. R. Quermann--U.S. Pat. No. 3,677,097--"Protective Stops For Flexure Suspended Gyroscopic Rotor", issued July 18, 1972.
These patents disclose concepts typical of the continuing trend of the design of gyroscopic instruments to achieve smaller, less expensive, and more reliable gyroscopic apparatus for employment in flight control and other precision navigation and stabilization applications.
The aforementioned patents, by way of example, illustrate that there are various ways in which a gyroscope rotor can be attached to a motor-driven shaft to permit angular deflection of the gyroscope rotor with respect to its drive axis and consequent measurement of the deflection for control purposes. Desirable properties for the suspension system include strength and rigidity in all translational directions so that the instrument is relatively immune to damage by acceleration, vibration, and shock. Further, a low spring restraint for the angular displacement system about the input axes is desired so that sensitivity is appropriately high. Further desired inherent qualities relate to isoelasticity, synchronous vibration sensitivity, and adaptability to the incorporation of inertial tuning. In designs using a simple spider radial support element and a cylindrical strut axial support element it is possible to achieve relatively low cost and low sensitivity to undesired effects, especially to twice-rotor-speed vibration, but this is at the expense of relatively high spring restraint. Alternatively, other suspensions that achieve low spring restraint and high translational rigidity require intricate and costly machined parts and redundant suspensions. Also, such configurations require precise balancing adjustment to achieve low sensitivity, especially to twice-rotor-speed vibration.